1. Field of the Invention
The present invention relates to a cutting edge measuring device for machine tool, and more particularly relates to a cutting edge measuring device which can be used for measuring a cutting edge position of tools while a workpiece is being gripped by a chuck provided in a main spindle of the machine tool.
2. Prior Art
Heretofore, there has been increasing demands on improvement of the accuracy for finished products. However, when improving the accuracy of the products, there exist various problems such as thermal distortion due to heat generated upon cutting and processing operations of a workpiece to be produced and tool abrasion. For this reason, cutting edge position of the tool displaced by thermal distortion or tool abrasion must be precisely detected and then compensation must be made for precise positioning of the cutting edge.
Various cutting edge measuring devices have been proposed such as shown in Japanese Laid-open Utility Model Publication No. 5-9804 and Japanese Laid-open Patent Publication No. 6-39686. These devices ensure measurement of a cutting edge of tools without interrupting a workpiece chucked in the main spindle of the machine tool.
However, the cutting edge measuring device disclosed in Japanese Laid-open Utility Model Publication No. 5-9804 has several drawbacks in that the operational performance of the device is insufficient and in that the measurement of a cutting edge position is not accurate. Because of the position where the cutting edge measuring device is provided and the stroke movement (numerical controlled) of the tool to the X-axis direction at the processing point, in this measuring device, measurement of a cutting edge position is carried out for the tool (provided on a tool rest through a turret) which positions oppositely to the working tool and is away from the cutting and processing position. Also in this arrangement, it is difficult for an operator to watch the measuring position where the detecting head of the cutting edge measuring device is contacting to the cutting edge of the tool, leading to deteriorated handling operation.
The cutting edge measuring device disclosed in Japanese Laid-open Patent Publication No. 6-39686 includes a touch sensor which rotates around the chuck. Therefore, the measuring device is large-sized and complicated in its construction, leading to difficulty for maintenance. Also in this measuring device, the touch sensor is likely to suffer from chips or coolant splashing during machining.
With the foregoing drawbacks of the prior art devices in view, the present invention seeks to provide a simple and small measuring device for a cutting edge of the tools provided on the tool rest, and which ensures measurement of the cutting edge while a workpiece is chucked in the main spindle. Also the present invention seeks to provide a cutting edge measuring device for machine tool which excels in operational performance, measuring accuracy and handling operation, and which is not subject to chips or coolant splashing during machining operation.